There is also the Grouping Object feature (see Poser Pro 2012 manual page 229, or Poser 9 manual, page 222)

It's basically an invisible, non-renderable prop that you can use as a parent to objects; but it does a bit more than that. For example, you can set it and its children to be invisible or non-renderable, etc. A small example is given in the manual for how you can use it.